The present invention relates generally to image-forming devices, and particularly to a paper feed mechanism of an image-forming device that employs continuous paper. The present invention is suitable, for example, for an output device for use with a computer system that needs to print large amounts of data.
Hereupon, the phrase, xe2x80x9ccontinuous paperxe2x80x9d, is intended to denote continuous-form paper in a folded stack, roll or other shapes, and an OHP film, or other types of recordable media that permit a user""s discretionary setting of a recording length. The width of the continuous paper has a standardized or predetermined dimension.
The electrophotographic image-forming device that uses continuous paper as a recordable medium (continuous paper printer) is utilized for printing (outputting) large amounts of data. In recent years, high-speed continuous paper printers that can create a printed output for a short time by printing out processed information received from networked small processors or main frames have become commercially practical. The continuous printer generally comprises a printing part, a paper feeder part, a conveyor part, and a collecting part.
The printing part, which adopts the electrophotographic method employing a photoconductive insulator (e.g., photosensitive drum, and photosensitive belt), follows the procedural steps of charging, latent image formation, development, transfer, and fixing. The charging step uniformly electrifies the photosensitive drum (e.g., at xe2x88x92700 V). The latent image formation step irradiates a laser beam or the like on the photosensitive drum based upon print data, and changes the electrical potential at the irradiated area down, for example, to xe2x88x9250 V or so, forming an electrostatic latent image. The development step electrically deposits a developer onto the photosensitive drum using, for example, the reversal process, and visualizes the continuous electrostatic latent image. The transfer step brings the photosensitive drum into continuous contact with continuous paper conveyed at the same speed as a circumferential velocity of the photosensitive drum, and continuously forms a toner image corresponding to the electrostatic latent image on the continuous paper using a transfer unit. The fixing step fuses and fixes the toner image on the continuous paper by the application of heat or pressure, or light irradiation by a fixing unit, thereby obtaining a printed matter.
The paper feeder part includes a hopper accommodating folded continuous paper. The conveyor part conveys the continuous paper from the paper feeder part to the collecting part through the printing part. The conveyor part typically includes an automatic loading part, and a conveyor roller. At both sides of the continuous paper are provided, for example, round apertures (sprocket holes), and the conveyor part includes conveyor pins and a pin roller (or belt with teeth) that corresponds to the apertures and moves in synchronous with rotation of the photosensitive drum, to convey continuous paper at high speed by fitting pins into the apertures of the continuous paper. During conveyance of continuous paper, the continuous paper is subjected to the processes in the transfer and fixing steps, and precisely synchronized operations between the conveyance of the continuous paper and the rotation of the photosensitive drum make a high-quality transfer possible. The collecting part includes a stacker that stores continuous paper that has been printed. The stacker also serves to eject the continuous paper that has been printed out of the device. The continuous paper that has been ejected out of the device undergoes a variety of processes such as cutting in a post-processor electrically connected with the continuous paper printer.
However, a conventional continuous paper printer is disadvantageously susceptible to a jam and image degradation. To be more specific, in the conventional continuous paper printer, an irregular load that would be applied to continuous paper when the conveyor part draws out the continuous paper from the hopper would pull the continuous paper in a direction opposite to the drawing direction. Accordingly, a conveyance speed of the continuous paper would vary, and thus a poor transfer results, or a local application of the above load would cause the continuous paper to swerve from a conveyance route, and produce a jam. A description will now be given of loads applied to the continuous paper, with reference to FIGS. 7 through 9.
Continuous paper P is stored in a hopper 1 so that each folded side may come into contact with wall surfaces of the hopper 1 so as to prevent the continuous paper P from moving in the hopper 1, and affecting the conveyance. When the continuous paper P is drawn out from the hopper 1, if the uppermost fold of the continuous paper P were not in contact with the wall of the hopper 1 as shown in FIG. 7, the continuous paper P would be conveyed with no irregular load applied thereto.
Faster printing processes demanded in recent years require increased speed at conveying the continuous paper P. Fast conveyance would generate vibrations in the continuous paper P, and often cause the continuous paper P to be drawn out with the fold kept in contact with the wall surface of the hopper 1. If the continuous paper were conveyed with the fold kept in contact with the wall surface of the hopper 1, space formed with the wall surface of the hopper 1 and the continuous paper P would decompress as shown in FIG. 8, and thereafter, part of the continuous paper P would be adhered closely to the wall surface of the hopper 1 as shown in FIG. 9. This phenomenon would occur more frequently particularly when the amount of the continuous paper P stored in the hopper 1 becomes small. The closely adhered continuous paper P to the hopper 1 would cause an irregular load to be applied to the continuous paper P partially or entirely. Such a load would pull the continuous paper in a direction opposite to a drawing direction, and thus reduce the conveyance speed of the continuous paper that is being drawn out. Accordingly, the conveyance speed of the continuous paper P would vary. Consequently, a jam due to misaligned continuous paper P, or deteriorated image quality due to a poor transfer caused by loss of synchronism with the photosensitive drum would result. Hereupon, FIG. 8 is a schematic sectional view for illustrating decompressed space formed with the continuous paper P and the wall surface of the hopper 1. FIG. 9 is a schematic sectional view for showing the continuous paper P adhered closely to the hopper 1.
In order to prevent such adhesion of the continuous paper P to the hopper 1, holes that allow air to flow through the wall of the hopper 1 might possibly be formed to prevent the decompression. However, this would be impractical due to disadvantages such as a possible increase in costs of hoppers as accompanied by recent year""s diversification of recordable media, and continuous printers"" incapability of using a variety of hoppers.
As shown in FIG. 10, a roller pair might be provided directly above the continuous paper P stored in the hopper 1 to regulate a conveyance route of the continuous paper P. FIG. 10 is a schematic sectional view for showing a conventional swing prevention mechanism for continuous paper P. The roller pair includes an immovable roller unit 2 and a movable roller unit 3. The immovable roller unit 2 is anchored perpendicularly on a main body housing of the continuous paper printer, and includes at a distal end thereof a roller portion 2a, which may rotate while keeping in contact with the continuous paper P. The movable roller unit 3 is joined via a joint 4 to the housing of the continuous paper printer, and is manually pivotable about the joint 4 as indicated by a dotted line and a solid line. The movable roller unit 3 also includes at a distal end thereof a roller portion 3a, which may rotate while keeping in contact with the continuous paper P. During the conveyance, the roller portion 2a of the immovable roller unit 2 and the roller portion 3a of the movable roller unit 3 are located at the same height from the continuous paper P. When the continuous paper P is replenished, on the other hand, the movable roller unit 3 is manually moved away to a position indicated by the dotted line. After the continuous paper P is replenished, the movable roller unit 3 is manually moved to a position indicated by the solid line. This roller pair serves to regulate a conveyance route of the continuous paper P, and thus may prevent the continuous paper P from being adhered to the hopper 1. However, since a height of the roller portion 2a cannot be changed, the hopper 1 that accommodates, for example, more than three thousand sheets of continuous paper P cannot be used with this roller pair. Moreover, the manual operation of the movable roller unit 3 would possibly induce a human based error. Further, the units 2 and 3 are optionally applied to a continuous paper printer, and each unit is configured to be detachably attachable independently; therefore the device is not configured as a whole to be a movable mechanism that moves vertically. Accordingly, as printing proceeds, a distance between the roller portion 2a and a top of a folded stack of continuous paper P would increase, and thus the regulatory effect produced by the units 2 and 3 would decrease.
Therefore, it is an exemplified general object of the present invention to provide a novel and useful guide mechanism, paper feed control method, and image-forming device in which the above conventional disadvantages are eliminated.
Another exemplified and more specific object of the present invention is to provide a guide mechanism, paper feed control method, and image-forming device that can prevent a jam and image degradation from occurring.
In order to achieve the above objects, a guide mechanism as one exemplified embodiment of the present invention comprises a guide part that guides continuous paper from a paper feeder part storing the continuous paper to a conveyor part, while regulating a conveyance route of the continuous paper; and a driving part that drives the guide part and the paper feeder part to relatively and automatically move according to a storage amount of the continuous paper in the paper feeder part. Since the driving part can move relatively and automatically within a distance between the guide part and the paper feed part according to this guide mechanism, for instance, the guide part may be moved away so as not to hinder a user""s operation such as replenishing the continuous paper. Moreover, the driving part can automatically move the guide part and/or the paper feed part, and thus human based errors due to manual movement can be avoided.
A paper feed control method as another exemplified embodiment of the present invention comprises the steps of determining space between a guide part that regulates a conveyance route of continuous paper, and a stack of the continuous paper; controlling a driving part to keep the space between the guide part and a stack of the continuous paper at a given distance; and controlling the driving part under a specified condition to automatically set the space between the guide part and a stack of the continuous paper apart to a specified distance not less than the given distance. During conveyance of the continuous paper, a distance between a stack of the continuous paper and the guide part can be kept constant, and the regulatory effect of the guide part can be maintained irrespective of the remaining amount of the continuous paper. Automatically spacing not less than a specified distance between the guide part and a stack of the continuous paper under a specified condition would allow the guide part to be moved away. Such moving away operation would prevent the guide part from hindering a user""s operation and facilitate the user""s setting of the continuous paper.
An image-forming device as one exemplified embodiment of the present invention comprises: a paper feeder part that stores continuous paper; a conveyor part that conveys the continuous paper from the feeder part; a guide part that is provided between the paper feeder part and the conveyor part, and guides the continuous paper to the conveyor part, while regulating a conveyance route of the continuous paper; a driving part that drives the guide part and the paper feeder part to relatively move according to a storage amount of the continuous paper; and a printing part that forms an image on the continuous paper fed from the paper feeder part through the guide part. This image-forming device exhibits the same operation as the above guide mechanism.
Other objects and further features of the present invention will become readily apparent from the following description of the embodiments with reference to accompanying drawings.